Not to mention it creates laziness. I feel that it creates an attitude of not following through on things. You really don't want to go on those calls, and it is potentially dangerous and always pointless to do what it takes to get those people through to baptism. Usually, you fail--learned helplessness that carries through. Thus, most witlesses simply dog finding their calls or finding people at home in the first place.
Then, when they have a real issue in real life, the attitude carries through. This time, the benefit is real--making decent money, moving away from your parents or to another country as the need arises, investing your money in something that will appreciate in value, studying, and the like. You were trained to put little effort in following through--getting started is easy, but keeping going is where things usually fall apart. The usual result in too many cases is that people go right back into the cancer, to do more piddling field circus. It also prevents people from success, because they are trained to dog things involving following through.
I agree fully that they are a scourge on mankind. They are a general nuisance, intruding on people at home when they are working or enjoying their time, infringing on people at parks and other public places (so they can't really enjoy the time), and wasting people's time everywhere. They also harm children--beyond molesting them, they take away all their fun (which does more damage because everyone is affected). They train people to not do anything worthwhile for society (in addition to teaching them helplessness) by preaching them to waste their time in field circus. They do not allow people to start their own businesses--even in countries where doing so is relatively easy. Yet, they encourage the members to go on welfare so they can do more for Jehovah.